Rust: Avoid path resolution in Element.toString by hvitved · Pull Request #22520 · github/codeql

hvitved · 2026-09-07T12:33:07Z

This PR removes the dependency on evaluating path resolution when evaluating Element.toString (and hence any query whatsoever). The dependency happened because the root def of Element.toString() had a fallback call to getAPrimaryQlClass, which in turn requires evaluating path resolution (e.g. here).

This PR avoids the root def call by instead pushing those calls down to classes that are currently lacking a proper toString implementation, and to help verify my changes I also added a new consistency check for missing toString implementations, which revealed existing bugs that could all be handled by adding concat(...) wrappers to account for missing AST children.

DCA shows that we have a few more AST inconsistencies (because of the newly added check), but also that data flow inconsistencies go down (because of an existing data flow consistency check for missing toString), but most importantly DIL sizes decrease as expected.

Define string representations on concrete element classes, make existing renderers total when unresolved child data is absent, and remove the path-resolution-dependent fallback from Element. Add a consistency check for elements that lack a string representation and update generated-file metadata for customized wrappers. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

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🟡 Changes recommended

Attribute-macro item placeholders now dispatch to incomplete concrete strings such as fn instead of their dedicated representation.

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Review tier: Balanced
Findings: 1

New issues introduced by this change (1)

Severity	Finding
	`rust/ql/lib/codeql/rust/elements/internal/ItemImpl.qll` — This no longer preserves the special string for attribute-macro placeholders. For a placeholder…

What changed in this PR

Removes the global path-resolution dependency from Rust AST Element.toString() by moving fallback formatting to concrete element classes.

Changes:

Replaces the root fallback with concrete toStringImpl implementations.
Handles incomplete AST children with concat.
Adds missing-toString consistency diagnostics and updates test baselines.

File	Description
`rust/ql/test/query-tests/diagnostics/AstConsistencyCounts.expected`	Adds the new consistency count.
`rust/ql/test/extractor-tests/macro-in-library/PrintAst.expected`	Updates macro-call output.
`rust/ql/test/extractor-tests/macro-expansion/test.expected`	Updates macro-expansion strings.
`rust/ql/test/extractor-tests/macro-expansion/PrintAst.expected`	Updates printed macro placeholders.
`rust/ql/lib/codeql/rust/internal/AstConsistency.qll`	Detects missing string representations.
`rust/ql/lib/codeql/rust/elements/internal/YieldExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/YeetExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/WherePredImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/WhereClauseImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/VariantListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/UseTreeListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/UseImpl.qll`	Handles missing use trees.
`rust/ql/lib/codeql/rust/elements/internal/UseBoundGenericArgsImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/UnsafeMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TypeBoundListImpl.qll`	Totalizes abbreviated output.
`rust/ql/lib/codeql/rust/elements/internal/TypeBoundImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TypeArgImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TupleTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TuplePatImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TupleFieldListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TupleFieldImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TupleExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TryExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TryBlockModifierImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TraitImpl.qll`	Handles missing trait names.
`rust/ql/lib/codeql/rust/elements/internal/TokenTreeMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/TokenTreeImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/StructPatFieldListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/StructImpl.qll`	Handles missing struct names.
`rust/ql/lib/codeql/rust/elements/internal/StructFieldListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/StructExprFieldListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/StmtListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/StaticImpl.qll`	Handles missing static names.
`rust/ql/lib/codeql/rust/elements/internal/SourceFileImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/SliceTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/SlicePatImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/SelfParamImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ReturnTypeSyntaxImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/RetTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/RenameImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/RefTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/RangePatImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/PtrTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/PathSegmentImpl.qll`	Totalizes abbreviated output.
`rust/ql/lib/codeql/rust/elements/internal/PathMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ParenTypeReprImpl.qll`	Handles missing inner types.
`rust/ql/lib/codeql/rust/elements/internal/ParenthesizedArgListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ParamListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/OffsetOfExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/NamedCrateImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ModuleImpl.qll`	Handles missing module names.
`rust/ql/lib/codeql/rust/elements/internal/MatchGuardImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MatchArmListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroRulesImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroPatImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroItemsImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroDefImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/MacroCallImpl.qll`	Handles missing macro paths.
`rust/ql/lib/codeql/rust/elements/internal/LifetimeParamImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/LifetimeArgImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/KeyValueMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ItemListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ItemImpl.qll`	Changes attribute-macro formatting dispatch.
`rust/ql/lib/codeql/rust/elements/internal/ImplImpl.qll`	Handles missing self types.
`rust/ql/lib/codeql/rust/elements/internal/FunctionImpl.qll`	Handles missing function names.
`rust/ql/lib/codeql/rust/elements/internal/ForTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/FormatArgsExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/FormatArgsArgNameImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/FormatArgsArgImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/FnPtrTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/FieldExprImpl.qll`	Handles missing field names.
`rust/ql/lib/codeql/rust/elements/internal/ExternItemListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ExternCrateImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ExternBlockImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ExprStmtImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/EnumImpl.qll`	Handles missing enum names.
`rust/ql/lib/codeql/rust/elements/internal/ElementImpl.qll`	Removes the root string fallback.
`rust/ql/lib/codeql/rust/elements/internal/DynTraitTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ConstParamImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ConstImpl.qll`	Handles missing constant names.
`rust/ql/lib/codeql/rust/elements/internal/ConstBlockPatImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ConstArgImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ClosureExprImpl.qll`	Handles missing closure bodies.
`rust/ql/lib/codeql/rust/elements/internal/CfgMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/CfgCompositeImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/CfgAttrMetaImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/CfgAtomImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AttrImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AssocTypeArgImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AssocItemListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmSymImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmRegSpecImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmRegOperandImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmOptionsListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmOptionImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmOperandNamedImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmOperandExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmLabelImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmExprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmDirSpecImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmConstImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AsmClobberAbiImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ArrayTypeReprImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ArrayExprInternalImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/ArgListImpl.qll`	Adds a class-name fallback.
`rust/ql/lib/codeql/rust/elements/internal/AbiImpl.qll`	Adds a class-name fallback.
`rust/ql/.gitattributes`	Reclassifies customized wrappers.
`rust/ql/.generated.list`	Removes customized wrappers from generation tracking.

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paldepind

This PR avoids the root def call by instead pushing those calls down to classes that are currently lacking a proper toString implementation, and to help verify my changes I also added a new consistency check for missing toString implementations, which revealed existing bugs that could all be handled by adding concat(...) wrappers to account for missing AST children.

Some of these I don't really understand. For instance, when will a closure expression not have a body? Is it for broken code that rust-analyzer parses anyway?

For some of the concat usages the strings will have trailing spaces when children are missing. For instance, an enum without a name will stringify as "enum ". However, if the cases are broken code, then I guess we don't care?

hvitved · 2026-09-09T08:54:14Z

Some of these I don't really understand. For instance, when will a closure expression not have a body? Is it for broken code that rust-analyzer parses anyway?

I think it is mostly for things inside macro expansions, but not sure exactly.

For some of the concat usages the strings will have trailing spaces when children are missing. For instance, an enum without a name will stringify as "enum ". However, if the cases are broken code, then I guess we don't care?

Yes, that's what I think.

github-actions Bot added the Rust Pull requests that update Rust code label Sep 7, 2026

hvitved force-pushed the hvitved-rust-tostring-implementations branch 5 times, most recently from 0d5bb66 to f9d728d Compare September 8, 2026 08:18

hvitved force-pushed the hvitved-rust-tostring-implementations branch from f9d728d to c05fc73 Compare September 8, 2026 13:14

hvitved added the no-change-note-required This PR does not need a change note label Sep 9, 2026

hvitved marked this pull request as ready for review September 9, 2026 08:30

hvitved requested a review from a team as a code owner September 9, 2026 08:31

Copilot AI balanced review requested due to automatic review settings September 9, 2026 08:31

Copilot started reviewing on behalf of hvitved September 9, 2026 08:31 View session

Copilot AI reviewed Sep 9, 2026

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Comment thread rust/ql/lib/codeql/rust/elements/internal/ItemImpl.qll

paldepind approved these changes Sep 9, 2026

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hvitved merged commit 2294b39 into main Sep 9, 2026
21 checks passed

hvitved deleted the hvitved-rust-tostring-implementations branch September 9, 2026 08:54

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Rust: Avoid path resolution in Element.toString - #22520

Rust: Avoid path resolution in Element.toString#22520
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hvitved commented Sep 7, 2026 •

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